Domestic appliance comprising an actuator connected to a base frame via leaf springs

ABSTRACT

A domestic appliance, such as a steam iron or a coffee making apparatus. The appliance comprising a housing, a water reservoir, an actuator, and a boiler for providing hot water or steam for an appliance. An input of the actuator is connected to the water reservoir, an output of the actuator is connected to an inlet of the boiler. In operation, the actuator introduces vibrations which are transmitted to the housing and radiated by the housing to the environment which cause unwanted sounds and noise. The unwanted sounds and noise induced by these vibrations is substantially reduced via two leaf springs mounted at opposite sides of the actuator which reduce the transmission of the vibrating energy by moving the actuator in a direction opposite to a direction of the movement of the drive member.

CROSS-REFERENCE TO PRIOR APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/233,313, (published as U.S. Patent Application PublicationNo. US 2014/0157956), filed Jan. 16, 2014, which is the U.S. NationalPhase application under 35 U.S.C. § 371 of International Application No.PCT/IB2012/053675, filed on Jul. 19, 2012, which claims the benefit ofU.S. Provisional Patent Application No. 61/509,157 filed Jul. 19, 2011.These applications are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a domestic appliance comprising a base frameand an actuator connected to the base frame.

BACKGROUND

Domestic appliances such as a coffee making machine or a steam iron forgarment care are used by a user to facilitate tasks.

EP-0135484 discloses a steam iron comprising a sole plate, a waterreservoir and a boiler wherein the plunger pump is arranged to pumpwater from the reservoir to a steam generator.

In operation, for example when a user applies steam to the garment, theactuator, i.e. the plunger pump reciprocally moves the plunger to pumpwater from the water reservoir to the boiler, which in turn deliverssteam to the garment.

The operating plunger pump generates sound and vibration which can beannoying to a user of the domestic appliance and to people present inthe environment of the user, and is not user friendly.

It is known from EP0135484 to provide a domestic appliance comprising abase frame, an actuator connected to the base frame, the actuator beingprovided with a drive member, the actuator being arranged forreciprocating movement of the drive member at a reciprocating frequency.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a domesticappliance that, in operation, has a reduced level of sound andvibration.

According to the invention this and other objects are achieved by,providing a domestic appliance that further comprises two leaf springsmounted at opposite sides of the actuator for connecting the actuator tothe base frame and enabling the actuator to move in a direction oppositeto a direction of the movement of the drive member, the actuator, thedrive member and the leaf springs together forming a mass spring systemhaving a natural frequency (f_(n)), wherein a stiffness of the leafsprings is adapted so that a ratio between the reciprocating frequency(f_(r)) and the natural frequency (f_(n)) is at least √2. The actuatorcan be for example a plunger pump or a diaphragm pump.

In general, noise originating from the domestic appliance can be deducedto air born noise and structure born noise. By reducing the transmissionof the vibrating energy induced by the actuator to the base frame of thedomestic appliance, the structure born noise can be substantiallyreduced, resulting in a lower sound level of the domestic appliance.

The force transmission from the vibrations from the reciprocatingactuator via the leaf springs to the frame can be modeled by a massspring system with one degree of freedom with a natural frequency fndetermined by

fn=(½π)*√(k/m) wherein

k represents the stiffness of the leaf springs andm represents the total mass of the actuator and the drive memberthereon.

This natural frequency fn of the mass spring system is dimensioned at afrequency below the reciprocating frequency fr of the actuator byadapting the stiffness of the leaf springs. For an effective reductionof the transmission of forces from the actuator to the base frame theratio between the reciprocating frequency and the natural frequencyfr/fn is at least √2 and damping should be minimal.

In this arrangement the vibration energy of the actuator is stored asenergy in a mass spring system consisting of the actuator, the drivemember and the leaf springs, so that the transmission of thesevibrations to the base frame is reduced, resulting in a lower soundlevel of the domestic appliance.

The cited documents EP-0135484 discloses a steam iron wherein the pistonpump is supported by two spaced rubber flanges to reduce the sound levelof the reciprocating piston pump. In the steam iron disclosed in thatdocument the rubber flanges are designed for substantially absorbing thevibrating energy of the actuator, however the vibrations is still partlytransmitted to the base frame. That document does not disclose two leafsprings connected to opposite ends of the actuator.

In a further embodiment of the domestic appliance the leaf springscomprise a bended end portion. Bended end portions of the leaf springsprovide a compact arrangement of the actuator and leaf springs.

In a further embodiment of the domestic appliance the end portions ofthe leaf springs that are connected to the actuator conform a U-shape.

In a further embodiment of the domestic appliance the actuator isconnected to the leaf-springs via elastomer members. These elastomermembers can be for example rubber rings.

In a still further embodiment of the domestic appliance, the domesticappliance further comprises a water reservoir provided at the baseframe, the water reservoir being operationally connected to the actuatorvia a first flexible tube. In a further embodiment of the domesticappliance the water reservoir is detachably mounted at the base frame.This arrangement facilitates easy refilling of the water reservoir.

In a further embodiment the first flexible tube comprises a corrugatedtube. A corrugated tube has a high flexibility and reduces transmissionof vibrations from the actuator to the base frame via the corrugatedtube.

In a still further embodiment of the domestic appliance, the domesticappliance further comprises a boiler for water heating or steamgeneration mounted at the frame and operationally connected to theactuator via a second flexible tube.

In a still further embodiment of the domestic appliance, the actuatorcomprises a plunger pump or diaphragm pump.

In further embodiment of the domestic appliance the actuator comprises aplunger pump, and the drive member comprises the plunger.

These and other features and effects of the present invention will beexplained in more detail below with reference to drawings in whichpreferred and illustrative embodiments of the invention are shown. Theperson skilled in the art will realize that other alternatives andequivalent embodiments of the invention can be conceived and reduced topractice without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic illustration of a steam iron according to afirst embodiment;

FIG. 2 shows a schematic illustration of a leaf spring; and

FIG. 3 shows a schematic illustration of a coffee making apparatusaccording to a second embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

In the figures like numerals refer to similar components.

FIG. 1 shows a steam iron 1 comprising a base frame, for example anhousing 3, an actuator, for example, a plunger pump 5 connected to thehousing 3 via leaf springs 21,23. The steam iron 1 may be provided witha water reservoir 9 mounted at the housing 3. An outlet of the waterreservoir 9 is connected to an inlet of the plunger pump 5 via a firstflexible tube 11. The first flexible tube 11 may be a corrugated tube.The water reservoir 9 may be detachably connected to the housing 3 forenabling refilling with water by removing the water reservoir 9 from thehousing 3, filling the water reservoir 9 and attaching the waterreservoir with the housing 3. Furthermore, the steam iron 1 comprises aboiler 13 for heating water or generating of steam. An inlet of theboiler 13 is connected to an outlet of the plunger pump 5 via a secondflexible tube 15. An outlet of the boiler 13 is connected to the iron 19via a third flexible tube 17 for dispensing steam. The plunger pump 5may comprise an elongated pump house 6 and a plunger 8. In thisembodiment the elongated pump house 6 is connected to the housing 3 viathe two leaf springs 21,23 mounted in a longitudinal direction atopposite sides of the elongated pump house 6. The leaf springs 21,23enables the pump house 6 to move in a horizontal direction opposite to adirection of movement of the plunger 8 and parallel to the longitudinalaxis of the pump house 6.

In operation, the plunger 8 is usually reciprocating at the mainsfrequency which can be, for example, 50 or 60 Hz. The reciprocatingplunger 8 causes reaction forces of the pump house 6 to act on the leafsprings 21,23 and deflect the leaf springs in a longitudinal directionopposite to the movement of the plunger 8. The deflected leaf springs21,23 stores kinetic energy of the vibrations as potential energy, whichis released as the plunger 8 moves in an opposite direction. The leafsprings 21,23 isolate the plunger pump 5 from the housing 3 and thetransmission of vibrations from the plunger pump 5 to the housing 3 issubstantially reduced.

The transmission of vibrations of the reciprocating plunger pump 5 viathe leaf springs 21,23 can be modeled by a mass spring system with onedegree of freedom with a natural frequency fn determined by

fn=(½π)*√(k/m) wherein:

k represents the stiffness of the leaf springs 21,23 andm represents the total mass of the plunger pump 5 and the plunger 8.

This natural frequency fn of the mass spring system is dimensioned at afrequency substantially below the reciprocating frequency fr of theplunger 8 by adapting the stiffness of the leaf springs 21,23 and thetotal mass of the plunger pump 5. For a reduction of the transmission ofvibrations from the plunger pump 5 to the housing 3 the ratio fr/fnbetween the reciprocating frequency fr and the natural frequency fn isat least √2. For example, in case the ration fr/fn equals 10 and thereciprocating frequency fr of the plunger pump is 50 Hz, the naturalfrequency fn of the mass spring system should be dimensioned at 5 Hz.The actual dimensions of the leaf springs 21,23 depends on the mass ofthe plunger pump 5, the reciprocating frequency, and the Young's modulusof the material of the leaf springs 21,23 and the maximal allowedamplitude of the movement of the plunger pump 5 in the housing 3. Inthis embodiment vibrating energy is stored in the moving pump house 6and the leaf springs 21,23. The internal damping of the leaf springs21,23 restricts the maximum amplitude of the horizontal movement thepump house 6. The leaf springs 21,23 can be made of corrosion freespring steel. The noise reduction that can be obtained in thisarrangement is about −40 dB(A) in the direction of the movement. Inpractice this maximal reduction also depends on the productarchitecture.

FIG. 2 shows a schematic illustration of one the leaf springs 21. Theleaf springs 21,23 can be mounted at the opposite sides of the housing 6of the plunger pump 5 via elastomer members, for example rubber rings25,27 at both sides of an end portion 29 of the respective leaf springs21,23 for further damping of vibrations. The elastomer rings 25,27 maybe made of synthetic material like Ethylene Propylene Diene Monomer(EPDM) or Nitrile Polymer Rubber (NPR) of mid-range hardness (50-50Sh-A). The leaf springs 21, 23 are mounted at the opposite sides of thehousing 6 of the plunger pump 5 at an attachment surface that iscoextensive with the elastomer rings 25, 27.

The leaf springs 21,23 may comprise bended end portions 29 which areconnected to the housing 6 of the plunger pump 5. For example, the endportions 29 of the leaf spring 21 may conform to a U-shape in order toobtain a compact configuration of the plunger pump 5 and leaf springs21,23. Instead of a U-shape, the end portions 29 may conform to aV-shape or Z-shape. The bended end portions 29 of the leaf springscomprise a first and second leg of the U-shape.

FIG. 3 shows a coffee making apparatus 30 comprising a base frame, forexample a housing 32, an actuator, for example, a plunger pump 5,connected to the housing 32 via leaf springs 21,23 mounted at oppositesides of the plunger pump 5.

The plunger pump 5 may comprise an elongated pump house 6 and a plunger8. The leaf springs 21,23 enables the plunger pump 5 to move inhorizontal direction opposite to a direction of a movement of theplunger 8 and parallel to a longitudinal axis of the pump house 6. Thecoffee making apparatus 30 may be provided with a water reservoir 9mounted in the housing 32, an outlet of the water reservoir 9 isconnected to an inlet of the plunger pump 5 via a first flexible tube 11or corrugated tube. The water reservoir 9 may be detachably mounted atthe housing 32 to facilitate easy refilling. Furthermore, the coffeemaking apparatus 30 comprises a boiler 13 for heating water. An inlet ofthe boiler 13 is connected to an outlet of the plunger pump 5 via asecond flexible tube 15. An outlet of the boiler 13 is connected via athird tube 17 to a coffee pad holder 34 for dispensing hot water.

In operation, the plunger pump is normally reciprocating at the mainsfrequency of for example 50 or 60 Hz. The leaf springs 21,23 reducetransmission of vibrations from the plunger pump 5 to the housing 32 andreduction of structure born noise.

The leaf springs 21,23 may be of a similar type as the leaf springsdescribed with relation to FIG. 2. The leaf springs can be connected atopposite sides of the pump house along longitudinal direction.Furthermore, dimensioning of the leaf springs 21,23 in this embodimentis explained in the above description of the embodiment relating to FIG.1.

In the above described embodiments of the steam iron 1 and coffee makingapparatus 30 the plunger pump 5 may be replaced by a diaphragm pump. Theamount of vibration reduction that can be achieved is about −40 dB inthe direction of the movement.

The practical reduction in sound level that can be obtained would belower and is dependent on the product architecture and the side and/orsurface of the base frame. Although illustrative embodiments of thepresent invention have been described with reference to the accompanyingdrawings, it is to be understood that the invention is not limited tothese embodiments. Various changes or modifications may be effected byone skilled in the art without departing from the scope or the spirit ofthe invention as defined in the claims. Accordingly, referencethroughout this specification to “one embodiment” or “an embodiment”means that a particular feature, structure or characteristic describedin connection with the embodiment is included in at least one embodimentof the present invention. Thus, the appearances of the phrases “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.Furthermore, it is noted that the particular features, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

1. A domestic appliance comprising: a base frame, an actuator connectedto the base frame, the actuator being provided with a drive member, theactuator being arranged for reciprocating movement of the drive memberat a reciprocating frequency (f_(r)), wherein the domestic appliancefurther comprises a first leaf spring and a second leaf spring, thefirst leaf spring being connected at a first end of the actuator at afirst end surface in an axial direction along a direction of a movementof the drive member, the first leaf spring being connected at a secondend to the base frame at a first interface, wherein first leaf springextends perpendicular to the axial direction of the actuator, the secondleaf spring being connected at a first end to the actuator at a secondend surface of the actuator, opposite said first distal end surface, thesecond leaf spring being connected at a second end to the base frame ata second interface, whereby the second leaf spring extends perpendicularto the axial direction of the actuator, the first and second leafsprings enabling the actuator to move in a direction opposite to adirection of the movement of the drive member, wherein the end portionsof the first and second leaf springs that are connected to the actuatorconform to a U-shape, wherein the drive member causes reaction forces ofthe actuator to act on the first and second leaf springs to deflect thefirst and second leaf springs in a longitudional direction opposite themovement of the drive member, in addition to the actuator forcesdeflecting the first and second leaf springs in the horizontaldirection, the reaction forces further cause a residual widening of theopening of the U-shape of the first and second leaf springs from aninitial substantially bent shape towards a straight line shape, theactuator, the drive member and the leaf springs together forming a massspring system having a natural frequency (f_(n)) wherein a stiffness ofthe leaf springs is adapted so that a ratio between the reciprocatingfrequency (f_(r)) and the natural frequency (f_(n)) is at least √2 butno more than 10, wherein the first and second leaf springs compriserespective first and second attachment surfaces formed in a first leg ofthe U-shape, wherein the first and second attachment surfaces areattached to the first and second end surfaces of the actuator,respectively, via a first elastomer member positioned directly betweenthe first attachment surface and the first end surface of the actuator,and via a second elastomer member positioned directly between the secondattachment surface and the second end surface of the actuator, whereinthe base frame comprises a first flexible tube and the first flexibletube comprises a corrugated tube having a flexibility for reducingtransmission of vibrations from the actuator to the base frame, whereindimensions of the leaf springs depend on a mass of the actuator member,the reciprocating frequency (f_(r)), a Young's modulus of a material ofthe leaf springs and a maximal allowed amplitude of the movement of theactuator in the base frame.
 2. The domestic appliance according to claim1, wherein the leaf springs comprise a bended end portion.
 3. Thedomestic appliance according to claim 1, wherein the domestic appliancefurther comprises a water reservoir provided at the base frame, thewater reservoir being operationally connected to the actuator via thefirst flexible tube.
 4. The domestic appliance according to claim 3wherein the water reservoir is detachably mounted at the base frame. 5.The domestic appliance according to claim 1 wherein the domesticappliance further comprises a boiler for water heating or steamgeneration provided at the base frame, the boiler being operationallyconnected to the actuator via a second flexible tube.
 6. The domesticappliance according to claim 1 wherein the actuator comprises a plungerpump.
 7. The domestic appliance according to claim 1 wherein theactuator comprises a plunger pump and the drive member comprises theplunger.